GB2293979A

GB2293979A - Ball ejection machine

Info

Publication number: GB2293979A
Application number: GB9420820A
Authority: GB
Inventors: Henry Charles Pryor
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-10-14
Filing date: 1994-10-14
Publication date: 1996-04-17
Anticipated expiration: 2014-10-14
Also published as: GB9420820D0; GB2293979B

Abstract

A machine for ejecting a ball in a given direction comprises (a) at least three driveable rotatable members 9 (e.g. rollers) arranged to engage the ball to eject it from the machine, at least two of the members having non-parallel axes of rotation, and (b) means for driving the rotatable members at differential speeds and/or at differential ball engagement pressures to impart spin to the ball, whereby the spin axis of the ball when ejected can be selected by control of the differential speeds and/or engagement pressures to lie in any direction in a plane transverse to the direction of ejection. The rotatable members may have resilient rims arranged for frictional engagement with the ball, and may be provided by two pairs of opposed counter-rotatable rollers, each pair of rollers having a common plane of rotation. <IMAGE>

Description

BALL EJECTION MACHINE The present invention relates to a ball ejection machine, and more particularly to a ball ejection machine for the delivery of balls for use in the coaching of ball games such as cricket, tennis, baseball and squash.

Many popular ball games involve striking a moving ball.

During the coaching of pupils of such games, it is desirable to present to the pupil a series of balls each having the same delivery. This allows the pupil to perfect a particular shot.

Known are ball delivering machines comprising a pair of opposed counter-rotatable rollers. Examples of such machines include the machines described in patent specification GB 1363146 and UK patent application GB 2 095 565 A. Such machines are designed to reproducibly serve a ball in exactly the same direction a number of times.

In some ball games, the application of various types of spin to the ball constitutes an important element of the game. In cricket, for example, the application of spin is fundamental to the technique of slow bowlers. It is used to produce off break or leg break at the bounce.

To meet the need for a ball delivery machine which can apply spin to the ball, machines similar to those mentioned above have been designed which apply spin by rotating one roller at a higher speed than the other. An example of such a machine is the "BOLA" (TM) machine, shown in Figure 1.

Referring now to Figure 1, the "BOLA" (TM) machine comprises two opposed and counter-rotating wheels 2,4 (the direction of rotation is shown by the arrows). The wheels are spaced apart to define a channel 6. A ball 8 fed to the wheels is taken up by frictional engagement with the wheels 2,4 and driven in the direction of the arrow at high velocity.

The "BOLA" (TM) machine may impart spin to a ball about a single fixed axis which is parallel to the axes of rotation of the rollers by rotating one roller at a higher speed than the other. Thus, in order to vary the position of the spin axis of the ball (for example, to apply top spin rather than side spin) the orientation of the rollers must be varied to change the direction of their axes of rotation. Consequently, to obtain a different delivery the rollers of the machine must be moved.

In the case of the "BOLA" (TM) machine, this involves adjustment of the angle of the bowling head, as shown schematically in Figure 2(a)-(f). Here, the wheels are shown schematically in plan view from behind the machine.

The relative speeds of rotation of each wheel are indicated by the symbols "+" and "-". A "+" symbol indicates that the wheel is rotating relatively more quickly than a wheel bearing a "-" symbol.

The effect of the differential rotation speeds and orientations on the spin applied to the ejected ball is also shown schematically in Fig. 2(a)-(f) by an arrow on a ball viewed from behind. As shown, the trajectory of the ball is therefore into the paper. The name of the delivery produced is also indicated.

The reorientation of the wheels is time consuming, and usually necessitates careful manual re-aiming of the ball delivery by trial and error after the adjustments are made.

The present invention provides a machine for ejecting a ball in a given direction comprising; (a) at least three driveable rotatable members (e.g. rollers) arranged to engage the ball to eject it from the machine, at least two of the members having non-parallel axes of rotation, and (b) means for driving the rotatable members at differential speeds and/or at differential ball engagement pressures to impart spin to the ball, whereby the spin axis of the ball when ejected can be selected by control of the differential speeds and/or engagement pressures to lie in any direction in a plane transverse to the direction of ejection.

The provision of three or more rollers (at least two of which have non-parallel axes of rotation) enables two or more independently variable and intersecting vector components of torque to be applied to the ball simultaneously. Thus, in accordance with the principle of the parallelogram of forces, a resultant torque vector having a direction distinct from that of any of the component torques may be applied to the ball.

The direction of the resultant torque determines the direction of the axis of induced spin on the ball. It may be varied by adjusting the relative magnitudes of the component torques. This adjustment is achieved by changing the relative speeds of rotation of the rollers and/or the pressure which they apply to the ball (and thereby the extent of their grip thereon) during ejection. The axis of the spin induced on the ball can therefore be adjusted to lie in any direction in a plane transverse to the direction of ejection without altering the position of the rollers.

The present invention therefore permits a series of balls to be delivered, each having a different type of spin, without moving the position of the rollers. The machine is therefore suitable for remote controlled (and even programmed) servo-assisted operation and permits different shots to be practised or coached without long delays to alter the configuration of the rollers.

The rotatable members preferably have resilient rims arranged for frictional engagement with the ball, and are advantageously provided as two pairs of opposed counterrotatable rollers. This permits reliable coupling of the rollers with the ball and makes available the full range of spin axis directions without requiring unduly high tangential velocities for any one roller.

Each pair of rollers preferably has a common plane of rotation, and in preferred embodiments the axes of rotation of each pair of rollers are substantially parallel, the axes of rotation of one pair of rollers being substantially perpendicular to those of the other pair of rollers.

Conveniently, the rollers may take the form of wheels, though belts or drums may also be used. In order to provide for reliable coupling of the rollers with the ball, the rollers may be provided with a high-friction surface. In a preferred embodiment, the rollers are wheels having concave rims (e.g. concave polyurethane rims).

The machine may further comprise drive means for rotating the rollers. Conveniently, the drive means may rotate each roller independently, for example at a variable rotational speed of up to 3000 revolutions per minute.

The machine may also provide for engagement of the rollers with a ball at variable pressure. This may comprise means for varying the spacing between the rollers and thereby in use the pressure on a ball in frictional engagement therewith. By this means the extent of the grip of the rollers on the ball (and thereby the torque imposed) may be varied during ejection. This can supplement or replace the use of variation of the speed of rotation of the rollers to adjust the degree of torque applied to the ball.

Conveniently, the machine of the invention further comprises a feed means (for example a hopper or magazine) for delivering balls to the rollers. The machine is conveniently mounted on a platform with vertical and lateral adjustment means for aiming an ejected ball.

The machine of the invention may be used for ejecting cricket balls, tennis balls, squash balls or baseballs, for example in a method of delivering a ball (for example a cricket ball, baseball, squash ball or tennis ball) comprising the steps of rotating the rollers of a machine according to the invention and feeding the ball to the rollers such that the ball is ejected with a predetermined degree of spin, the spin axis being selected to lie in any one direction in a plane transverse to the direction of ejection.

The invention also relates to a method of delivering a ball (for example a cricket ball) comprising the steps of; (i) rotating the rotatable members of a machine according to the invention and (ii) feeding the ball to the rollers (e.g. by gravity) such that the ball is ejected with a predetermined degree of spin, the spin axis being selected to lie in any direction in a plane transverse to the direction of ejection.

Also contemplated by the invention is an assembly for use in the machine according to the invention comprising an array of at least three driveable rotatable members (e.g.

rollers) arranged to engage a ball, at least two of the rotatable members having non-parallel axes of rotation.

The invention will now be described in more detail and by way of example only by reference to a specific embodiment. The embodiment will be described with reference to Figure. 3 to 5 of the accompanying drawings in which: Fig. 3 is a schematic plan view of the bowling head of a machine according to the invention.

Fig. 4 is a schematic perspective view of a machine according to the invention.

Figs. 5(a)-(g) are plans showing the different deliveries obtainable with the machine of the invention.

Referring now to Figs. 3 and 4, the bowling machine comprises a bowling head 1 mounted on a hanger 16 (Figure 4) having two pairs of orthogonally oriented opposed wheels 2,4 and 6,8 mounted on a backplate 14 via four motors 12. Each motor is subject to independent control via a remote control unit (not shown).

Each pair of wheels has a common plane of rotation, and their axes of rotation are essentially parallel. In the embodiment shown the wheels are 13" in diameter, though these can be exchanged for 10" diameter wheels in circumstances where lower ball velocities are sufficient.

The backplate 14 has a central aperture 15 fed by gravity from a hopper or magazine (not shown). The wheels 2,4 and 6,8 have resilient concave polyurethane rims 9 (as shown in Fig. 4) and are spaced apart to define a central passage 10 of a size suitable to permit passage of a cricket ball therethrough. The spacing of the rollers (and consequently the pressure applied to the ball by the wheels when passing through the passage 10) may be varied by motors (not shown). The passage 10 is advantageously of a somewhat smaller diameter than a cricket ball and this, together with the resiliency of the wheel rims 9, ensures that the wheels maintain a good grip on the ball during ejection.

The backplate 14 is mounted on a hanger 16 permitting tilt adjustment via hinges 17. The hanger 16 is mounted in a cage 18 supported on a support 22 having vertical height adjustment as well as lateral swivel adjustment 20.

In use, each of the two pairs of wheels 2,4 and 6,8 are counter-rotated in the direction shown by the arrows in Fig. 3 by the motors 12. The motors are arranged to rotate each wheel at a variable speed of up to 3000 rpm.

A cricket ball is then fed from the hopper or magazine located behind the backplate 14 to pass through the aperture 15 whereupon it is taken up by the wheels 2,4 and 6,8 and carried through the passage 10 to be ejected at high velocity.

The ejected ball may be aimed by tilting at hinges 17, by lateral swivelling at 20 and by adjusting the height of the support 22.

Different types of spin can be applied to the ball by varying the relative speeds of rotation of the wheels, or by varying the pressure applied to the ball by each roller. Figures 5(a)-(g) show different types of spin as applied by variation in the relative speeds of rotation of the wheels. Here, the bowling head is shown schematically as a plan view of the four wheels viewed from behind the machine. The relative speeds of rotation of each wheel are indicated by the symbols "+", "-" and "=". Wheels sharing any of the three symbols are rotating at the same speed. A "+" symbol indicates that the wheel is rotating relatively more quickly than a wheel bearing a - symbol. The "=" symbol is used to indicate that all wheels are rotating at the same speed.

The effect of the differential rotation speeds on the spin applied to the ejected ball is shown schematically by an arrow on a ball viewed from behind. As shown, the trajectory of the ball is therefore into the paper. No arrow is shown when the ball is not spinning (Fig. 5(a)).

The effect of the spin on the trajectory (and bounce characteristics, where appropriate) of the ball is also shown schematically using arrows. A bounce is indicated by a break in the continuity of the arrow. The name of the delivery is also indicated.

The bowling machine may be provided as a complete unit.

Conveniently, it may be provided as a set of components so that the appropriate wheel dimensions, drive motors and supports can be selected to permit the construction of a customized machine as appropriate for the sports and coaching required. Such a set of components may comprise an assembly for use in the machine of the invention comprising an array of at least three driveable rotatable members (e.g. rollers) arranged to engage a ball, at least two of the rotatable members having non-parallel axes of rotation.

Claims

CLAIMS:

1. A machine for ejecting a ball in a given direction comprising; (a) at least three driveable rotatable members (e.g. rollers) arranged to engage the ball to eject it from the machine, at least two of the members having non-parallel axes of rotation, and (b) means for driving the rotatable members at differential speeds and/or at differential ball engagement pressures to impart spin to the ball, whereby the spin axis of the ball when ejected can be selected by control of the differential speeds and/or engagement pressures to lie in any direction in a plane transverse to the direction of ejection.

2. A machine according to claim 1 wherein the rotatable members have resilient rims arranged for frictional engagement with the ball.

3. A machine according to claim 1 or claim 2 wherein the rotatable members are provided by two pairs of opposed counter-rotatable rollers.

4. A machine according to any one of the preceding claims wherein each pair of rollers has a common plane of rotation.

5. A machine according to any one of the preceding claims wherein the axes of rotation of each pair of rollers are substantially parallel.

6. A machine according to any one of the preceding claims wherein the axes of rotation of one pair of rollers are substantially perpendicular to those of the other pair of rollers.

7. A machine according to any one of the preceding claims wherein the rotatable members or rollers are wheels, for example having concave rims (e.g. concave polyurethane rims).

8. A machine according to claim 7 wherein the wheels have a diameter of 8 to 16 inches, for example 13 inches.

9. A machine according to any one of the preceding claims wherein the drive means is arranged to rotate each roller independently, for example at variable speed up to 3000 rpm.

10. A machine according to any one of the preceding claims wherein the drive means comprises an electric motor, for example four electric motors.

11. A machine according to any one of the preceding claims further comprising means for varying the spacing between the rotatable members and thereby in use the pressure on a ball in frictional engagement therewith.

12. A machine according to any one of the preceding claims further comprising a feed means (for example a hopper or magazine) for delivering balls to the rollers.

13. A machine according to claim 12 wherein the feed means contains cricket balls.

14. A machine according to any one of the preceding claims further comprising a platform with vertical and lateral adjustment means for aiming an ejected ball.

15. A machine according to any one of the preceding claims further comprising programmable means (e.g. remote controlled programmable means) for controlling the differential speeds and/or engagement pressures of the rollers.

16. A method of delivering a ball (for example a cricket ball) comprising the steps of; (i) rotating the rotatable members of a machine according to any one of the preceding claims and (ii) feeding the ball to the rollers (e.g. by gravity) such that the ball is ejected with a predetermined degree of spin, the spin axis being selected to lie in any direction in a plane transverse to the direction of ejection.

17. An assembly for use in the machine according to any one of the preceding claims comprising an array of at least three driveable rotatable members (e.g. rollers) arranged to engage a ball, at least two of the rotatable members having non-parallel axes of rotation.

17. A ball ejection machine substantially as hereinbefore described with reference to Figures 3 and 4.

18. An assembly for use in the machine according to any one of the preceding claims comprising an array of at least three driveable rotatable members (e.g. rollers) arranged to engage a ball, at least two of the rotatable members having non-parallel axes of rotation.

Amendments to the claims have been filed as follows 1. A machine for ejecting a ball in a given direction comprising; (a) at least three driveable rotatable members (e.g. rollers) arranged to engage the ball so as to eject it from the machine, at least two of the members having non-parallel axes of rotation, and (b) means for driving the rotatable members at differential speeds to impart spin to the ball, whereby the spin axis of the ball when ejected can be selected by control of the differential speeds to lie in any direction in a plane transverse to the direction of ejection.

11. A machine according to any one of the preceding claims further comprising a feed means (for example a hopper or magazine) for delivering balls to the rollers.

12. A machine according to claim 11 wherein the feed means contains cricket balls.

13. A machine according to any one of the preceding claims further comprising a platform with vertical and lateral adjustment means for aiming an ejected ball.

14. A machine according to any one of the preceding claims further comprising programmable means (e.g. remote controlled programmable means) for controlling the differential speeds of the rollers.

15. A method of delivering a ball (for example a cricket ball) comprising the steps of; (i) rotating the rotatable members of a machine according to any one of the preceding claims and (ii) feeding the ball to the rollers (e.g. by gravity) such that the ball is ejected with predetermined degree of spin, the spin axis being selected to lie in any direction in a plane transverse to the direction of ejection.

16. A ball ejection machine substantially as hereinbefore described with reference to Figures 3 and 4.